There is an ever increasing amount of organic waste material produced in the world today. Managing the disposal of such waste in a safe and environmentally friendly manner and reclaiming any residual value in the waste is therefore a prime concern.
A known method for managing organic waste is through the process of pyrolysis, also known as gasification. Pyrolysis is the process of thermally degrading organic material in the absence of oxygen. This form of thermal degradation reduces waste volumes by converting the waste into ash so allowing easier disposal. What is more, pyrolysis can also produce organic fuels, such as hydrocarbon oils and gases, by way of by-product. The organic fuels may be reclaimed for other uses, thereby extracting value from the waste, or may be used to provide heat for the pyrolysis process itself, thereby making the process to some extent self-sustaining.
A known gasification apparatus, such as that disclosed in EP0851019, comprises two main components for the gasification process, namely a reaction chamber and a condenser unit. The reaction chamber is where the pyrolysis occurs, and the condenser unit, which is coupled to the reaction chamber, is where volatile hydrocarbons (e.g. oils and tar) liberated by the pyrolysis process are recovered.
In the known gasification apparatus, waste is fed through a rotating drum (the reaction chamber) containing a non-oxygen atmosphere. The drum is heated to a temperature of around 800° C. so that pyrolysis can take place. The drum is rotated to agitate the material so as to increase the pyrolytic efficiency, and also assist in the feeding of the material through the drum. This drum must, as far as possible, be free of oxygen for efficient pyrolysis to occur. However, this can be technically difficult to achieve in a rotating drum operating at relatively high temperature and with material continuously being fed into and out of the drum. Problems include sealing problems, lubrication problems and general reliability problems. Further problems with the known gasification apparatus are caused by oils and tar carried over from the reaction chamber (reactor) blocking the condensation unit. The condensation of the volatile hydrocarbon materials in the condensation unit impairs the efficiency of the condensation process and can lead to reliability and safety problems. There is therefore a need for an improved gasification apparatus and method.